Characteristics of Asian-African summer monsoon pre-and post-global warming in mid-1980s

For the global warming event sharpened in 1980s,this paper studied the differences of temperature and precipitation fields respectively between 1990-1995 and 1980-1985.Furthermore,this global warming event was compared with global cooling event in 1960s.The results showed that after mid-1980s,the global warming sharpened and the warmed areas included most of European-Asian continent except for the Tibetan Plateau,most of African continent and the south of Indian Ocean.Synchronously,the global precipitation had changed obviously too.Compared with the increase of summer rainfall over North of Africa during 1980-1985 and 1990-1995,that of northern area of North China increased while south area of it decreased,and the rainfall of north India decreased remarkably but that of the middle and south of India increased.In north of China and Sahel,it was showed that the rainfall during 1990-1995 increased,but was far smaller to reach that before mid-1960s.The differences of monsoon cells between 1990-1995 and 1980-1985 indicated that the African summer monsoon reinforced after global warming,but the Indian summer monsoon weakened evidently and the East Asian summer monsoon enhanced somewhat.On the basis of wavelet analyses of land-sea thermal contrast between Indian Ocean and Asian-African continent,summer precipitation over north of China and Sahel in African respectively,it was concluded that in 1960s,there were different in-phase interdecadal time-scale signals and they interacted to get reinforcement,thus the interdecadal oscillations played key role during this period;contrastively,in 1980s,there existed different decadal and interdecadal time-sclae signals which appeared opposite signs,so they counteracted with each other to become weak.Meanwhile it should be noted that the interannual signals reinforced remarkably in 1980s,so they became the most important signals and played key role in this event.Therefore,compared with climate event in 1960s,global warming in 1980s was not a simple out-of-phase interdecadal climate change event,but the different climate responses to different physical factors.